Overview of Preventive Interventions Addressing Underage Drinking

Because underage drinking is a serious public health concern and associated with numerous detrimental consequences, many interventions to prevent underage drinking have been developed. However, the effectiveness of all these interventions has not been proven. A recent review of the relevant literature that used stringent criteria for the types of studies and interventions included, as well as for the evaluation and classification of the studies, found that out of more than 400 studies screened, only 127 could be evaluated for efficacy and only 41 showed some evidence of effects. In addition, several areas were identified in which intervention research could be strengthened. For example, increased coverage is needed for understudied areas of intervention (e.g., specific types of interventions or interventions in specific populations). Other aspects of the knowledge base in this area that can benefit from further improvement include, among others, the availability of longitudinal studies, availability of information on alcohol-specific outcomes, or availability of replication studies. The standards for determining and reporting evidence of effectiveness in different studies also need to be clarified. Finally, prevention research needs to adopt public health impact–oriented models to accurately determine the potential of existing interventions to prevent underage drinking and its consequences.


U
nderage drinking is a serious public health concern, as demon strated by epidemiological data and results from studies investigating the social, health, and economic conse quences of drinking by children and adolescents.According to the Monitoring the Future Survey (Johnston et al. 2006), 41.0 percent of 8th graders, 63.2 per cent of 10th graders, and 75.1 percent of 12th graders in the United States reported that they already had consumed alcohol at some time in their lives, and 17.1 percent, 33.2 percent, and 47.0 percent, respectively, said they had con sumed alcohol in the month preceding the survey.Even more troubling was the finding that 6.0 percent of 8th graders, 17.6 percent of 10th graders, and 30.2 percent of 12th graders surveyed reported that they had been drunk in the 30 days prior to the survey (Johnston et al. 2006), indicating that particularly harmful drinking patterns already are highly prevalent during adolescence.
As is the case with adults, alcohol consumption in adolescents is associ ated with a range of detrimental consequences: • Adolescents who indulge in heavy drinking are more likely to engage in risky behaviors, such as drinking and driving.In fact, traffic crashes pose the single greatest mortality risk associated with underage drink ing (Grunbaum et al. 2002;Hingson and Kenkel 2004;Hingson et al. 2005).
• Underage drinking contributes to both unintentional and intentional injury deaths among adolescents (Hingson and Kenkel 2004).
• Adolescents who drink heavily are at increased risk of short and long term physical health problems, such as sexually transmitted diseases resulting from unprotected sexual activity (Dee 2001; Grunbaum et al. 2002;Hingson et al. 2005; National Institute on Alcohol Abuse and Alcoholism [NIAAA] 1993).
• Adolescents who drink are at increased risk for behavioral problems, including delinquency, violence, and poor aca demic performance (Hingson et al. 2002;Spoth et al. 2006; Substance Abuse and Mental Health Services Administration [SAMHSA] 2008;Swartzwelder et al. 1995).
• Underage drinking is associated with mental health problems, such as depression and suicidality (NIAAA 1997;Windle 1992;Windle and Windle 2001).
Consequences of underage drinking result in substantial economic costs, as well as other less tangible costs to the adolescent, his or her family, the community, and society as a whole.Although no definitive data are avail able, the economic costs of underage drinking have been estimated to be more than $62 billion (Foster et al. 2003;Levy et al. 1999).Other impor tant consequences of underage drink ing include potentially lasting effects on brain structure and function that may interfere with the adolescent's subsequent development (Tapert and Schweinsburg 2006;Tapert et al. 2008) and an increased risk of substance use during later adolescence as well as alcoholrelated disorders (i.e., alcohol abuse and alcohol dependence)and their associated problems-during adulthood (Grant and Dawson 1997).
All of these potential harmful con sequences and associated costs under score the importance of efforts to prevent underage drinking, using evidencebased preventive interven tions, along with appropriate policy measures.However, intervening is challenging because of the following: • Interventions must be designed and tested across developmental stages and a wide range of population sub groups considering that the needs and risk factors of, for example, a 10yearold Caucasian boy living in a small town in Oklahoma likely differ considerably from those of a 15yearold AfricanAmerican boy living in the Bronx, or from those of an 18yearold Hispanic girl liv ing in south Florida.
• Interventions must be designed to reduce risk factors and promote pro tective factors that delay initiation of alcohol use, which, in turn, reduces harmful adolescent drinking patterns and the likelihood of developing alcoholrelated problems during adulthood (Grant and Dawson 1997).
• A variety of effective interventions and policies operating at different levels must be developed, including comprehensive, communitylevel interventions.
• Interventions with demonstrated effectiveness must be effectively implemented on a large scale.
This article provides a comprehensive review of studies assessing the effec tiveness of existing underage drinking interventions in adolescents in three developmental periods (i.e., less than 10 years of age, 10 to 15 years of age, and 16 to more than 20 years of age, excluding studies on college samples that have been reviewed elsewhere [Larimer and Cronce 2007] 1 ).The goals of this review are to (1) highlight the compelling reasons for evidencebased preventive interventions targeting underage drinking, (2) review inter ventions that have shown evidence of effectiveness and efficacy, 2 and (3) discuss key findings and their impli cations from a public health perspective.
1 These agegroups are those that are targeted by the NIAAA Underage Drinking Initiative. 2 The efficacy of an intervention relates to whether the interven tion worked under the ideal and controlled conditions of a pre vention trial, with patients who were selected based on certain criteria and who were monitored to ensure that they received the intervention as prescribed, and in which the intervention was given by welltrained providers who followed the prescribed pro tocol.In contrast, effectiveness relates to whether the intervention worked under relatively more "reallife" conditions, with partici pants from a variety of backgrounds who may or may not have followed all the instructions and where the intervention was given by providers who may or may not have followed the regular protocol for the intervention.

Methods of Intervention Selection and Evaluation
The existing literature on alcohol and other drug-related preventive inter ventions for underage drinking is vast.This article summarizes the results of a comprehensive critical review of this literature to assess the evidence for effectiveness of existing interventions (Spoth et al. 2008).

Selection Criteria for Inclusion of the Interventions in the Analysis
Interventions included in the analysis reviewed here met the following criteria:

Evaluation Criteria for Classification of Studies
To determine how promising the evidence for the effectiveness of a given intervention was, six criteria were established according to which of the interventions were evaluated.These included the following: • Experimental design.Was the study a trial in which participants were ran domly assigned to the intervention or a control condition?Or did the study design include an adequate comparison group?
• Sample specification.Was there suffi cient information provided on the participants and their behavioral and social characteristics?
• Outcome assessment.Did the study include outcome data at a minimum of three different time points (i.e., before the intervention, after the intervention, and at a followup con ducted at least 6 months after the primary intervention implementation or postintervention assessment)?
• Effects observed.Was there a statisti cally significant difference in alcohol or alcoholrelated outcomes?• Manualization.Was there a written manual that specified the target pop ulation and intervention procedures?
Based on an overall judgment of how well these criteria were met, the reviewed interventions then were clas sified into one of three categories: (1) most promising evidence, (2) mixed or emerging evidence, and (3) insuffi cient evidence or no evidence of effects.To be classified as most promising, the interventions had to meet all six criteria listed (see Spoth et al. 2008, for a more detailed description of the criteria).Because many of these criteria cannot easily be measured, and some criteria may be more important than others, the classifica tion is based on an overall judgment of how well all criteria were met.Interventions that did not meet all the required criteria could be classi fied as mixed or emerging evidence.This was the case, for example, if the intervention demonstrated positive effects in some studies but no effects in other studies, or if within one study there were positive effects on some alcoholrelated measures but no effects on other measures.Similarly, interventions that yielded positive effects, but for which the studies had substantial methodological limita tions, and studies that found positive effects only for certain subgroups of the sample were classified as mixed or emerging evidence.Finally, all studies in which the intervention was aimed at adolescents younger than 10 years of age and that found an impact only on aggression, but not on later alcohol use, were classified as emerging.
Using this approach, a total of 12 interventions could be classified as most promising and 29 interventions as having mixed or emerging evidence; the remaining 86 interventions were classified as having insufficient evidence or no evidence of effects (see table 1).A brief summary of the most promis ing interventions is provided in table 2 (for additional information on studies with at least some evidence of effect, their samples, settings, results, and key sources, see Spoth et al. 2008).The reasons why most interventions were classified as having insufficient or no evidence of effects were wide ranging.For example, many studies had followup periods of less than 6 months; others demonstrated effects that were not statistically significant, had a weak experimental design, or failed to use alcoholspecific outcome measures.

Key Findings and Their Implications
One of the main results of these analyses was the finding that of more than 400 interventions identified only 127 could be assessed for evidence of effectiveness.Further, of those 127 only about one third demonstrated some evidence of positive effects, and of those about 10 percent could be classified as most promising.These findings suggest sev eral topics for further discussion and investigation.One of these is the extent to which the existing evidence covers the different agegroups of adolescents analyzed, different domains or settings in which interventions can be delivered (e.g., family, school, community, and media), and different subgroups of ado lescents (e.g., late teens, young adults not attending college, or minority pop ulations).A second issue concerns the state of the art in intervention research-for example, what research designs are being used and should be used.Finally, the ways in which research results are reported in the liter ature also need to be addressed.

Coverage of Understudied Areas of Intervention
This review of the evidence supporting the efficacy of existing interventions indicates that although much progress has been made in preventing alcohol use in underage populations, there still are gaps in understanding which type(s) of intervention, administered in which setting(s) and aimed at which target population(s), would be most effective in preventing underage drinking.
Researchers already have evaluated the relative advantages of different types of preventive interventions (i.e., universal versus selective versus indicated interventions).For example, Offord and colleagues (1998) discussed the key advantages of universal, selec tive, and indicated interventions and the tradeoffs among them. 3This assessment concluded that a universal intervention would likely be preferable over targeted or indicated interventions if the problem it addresses (e.g., under age drinking) is highly prevalent and associated with high costs, whereas the intervention itself is relatively inexpensive and has been shown to be effective.In general, Offord and colleagues (1998) suggested a tiered strategy involving implementation of effective universal interventions, sub sequent selective interventions for those who do not benefit sufficiently from the universal intervention, and indicated or clinical interventions for those who do not benefit from the selective interven tion and are at high risk of problems.
Intervention findings can be sum marized in numerous ways-for example, according to developmental period addressed (i.e., less than 10 years, 10 to 15 years, and 16 to more than 20 years), domain or setting in which the intervention is delivered (i.e., family, school, workplace, community, and multicomponent), or target population.The present review identified areas where evidence based intervention is relatively stronger or weaker by focusing on coverage of the different developmental phases within key domains.In addition, the extent to which special populations and culturally based population subgroups were covered by the existing evidence also was taken into consideration.et al. 2000, 2003], Seattle Social Development Project [Hawkins et al. 1991[Hawkins et al. , 1992]] For Parents and Youth 10-14 [Spoth et al. 2001[Spoth et al. , 2002[Spoth et al. , 2004[Spoth et al. , 2005]], Guiding Good Choices [Park et al. 2000;Spoth et al. 2001Spoth et al. , 2004]], and Family Matters [Bauman et al. 2000[Bauman et al. , 2001[Bauman et al. , 2002;;Ennett et al. 2001]).Interventions for this agegroup can either be home based or administered in small groups, and the analysis indicates that smallgroup interventions show relatively stronger evidence of effect (see Spoth et al. 2008).

FamilyFocused Interventions.
For older adolescents who are not going to college, no familyfocused interventions with evidence of effec tiveness could be identified, although other studies focusing on college bound adolescents have shown some effectiveness (Larimer and Cronce 2007).Thus, this is an area where additional research is greatly needed.

SchoolBased Interventions.
The area of schoolbased interventions has progressed significantly in recent years, and many interventions have been developed that include a variety of components, including life skills, peer refusal skills, roleplaying to practice new skills, strengthening positive peer relationships, provision of accurate norms for alcohol and other drug use, and support to improve the adolescent's emotional regulation.Such interven tions have been shown to significantly reduce aggression and disruptive behavior in younger children, as well as early initiation and progression of use in younger and older adolescents.
However, there still are some important limitations to these studies.For example, studies of interventions aimed at elementary school children have shown effects primarily on the risk factor of aggressive behavior, rather than subsequent alcohol use itself, at least in part because they only fol lowed participants for relatively short periods of time.Only a few studies monitored the participants into and through middle school (when alcohol use frequently is initiated) and thus were able to demonstrate effects on alcohol use.Additionally, there were no interventions with children in later elementary school years (i.e., grades 3 through 5) that focused on early alcohol use and which met the criteria for efficacy and effectiveness.Finally, only one schoolbased intervention targeted to highschool students could be classified as most promising and one could be classified as mixed or emerging evidence, indicating that interventions aimed at this agegroup, which often is affected by harmful drinking patterns such as binge drinking, is an area requiring substantially more research.

Multidomain Interventions.
Multidomain interventions focus on two or more different domains of the child's or youth's life (i.e., the individual, family, school, worksite, community/ environmental, or policy domain).This comprehensive approach is   (Hingson 1983), and fatalities (Decker et al. 1988).Other studies (Ruhm 1996;Vingilis and Smart 1981), however, found no changes in the rates of crashes and fatalities after the introduction of such laws, so the evidence remains inconsistent.Moreover, it is unclear if these laws actually reduced underage drinking or if the adolescents merely drank in different venues (i.e., at home rather than in a bar) or obtained alcohol through different channels (i.e., through parents or older friends rather than purchasing it themselves) after the laws were passed.As a result, these mea sures could not be classified as having most promising evidence of effect.

Conclusions
Despite substantial progress, the find ings presented here indicate that there still is very limited research on inter ventions that target emerging alcohol use among late elementary schoolaged children, highschool students, and older adolescents not currently in college.And although a wide range of domains were included in the analyses of interventions for highschool and post-highschool students, only a few theorydriven interventions targeted at this population could be identified.Moreover, although approximately one half of young adults ages 18-21 years in the United States (who tend to consume alcohol at high rates) do not attend college, few noncollege based interventions exist that target this agegroup.Thus, efforts to reduce underage drinking in this population are sorely missing, and additional work in this area is greatly needed.

Need for Additional Coverage of Cultural Adaptations and Special Populations
This review has demonstrated that there already are several interventions with promising or emerging evidence which have been designed to address the special needs of minority populations and other understudied populations (e.g., youth living in rural areas) or which otherwise address cultural adaptations (e.g., Keepin' It REAL).Nevertheless, the ability of many interventions to engage and influence youth from different cultural and ethnic backgrounds still needs to be enhanced, and for some developmental periods or target populations additional culturally specific interventions still need to be designed.Some of these changes may involve relatively super ficial modifications, such as changes in wording, pictures, or stories to make the intervention more relevant to certain cultural groups.Other modi fications, however, may affect the deeper structure of the intervention (e.g., the skills, attitudes, or policies to be conveyed) to meet the needs of different cultural groups.Finally, researchers need to demonstrate that alreadyproven, evidencebased models actually are effective across cultural groups.

Key Issues in Current Intervention Research
In recent years, researchers have paid increasing attention to improving research methodology (e.g., study design and data analysis) for evaluat ing the effectiveness of prevention interventions.For example, more studies are using designs in which participants randomly are assigned to interventions or control conditions (i.e., randomized studies), which enhances the credibility of the observed outcomes.Nevertheless, many studies still have significant limitations and gaps that are reviewed below and which need to be addressed in future prevention research.

Limited Longitudinal Studies.
One important issue is the implementation of rigorous studies that collect data over extended periods of time (i.e., longitudinal studies) to track both the initiation and progression of alcohol use.As mentioned earlier, many interventions targeting elementary school-aged children could not be included in the present review because their followup periods were too short.And even if some studies col lected followup data for more than 6 months, very few provided data that were extensive and regular enough to examine the longerterm effects of the interventions.Moreover, initiation and early growth of alcohol use follow different patterns over time than do development of heavy drinking or binge drinking.Accordingly, it is critical to study both of these processes across early to later adolescent periods.

Specificity in Logical Models.
Another concern is related to the rapid changes in alcohol use patterns during adoles cence, which contributes to inconsis tencies in findings across different assessments.For example, in some longitudinal studies, results of an intervention were mixed when data from different time points were compared or when different outcomes at one time point were compared.Because of this inherent variability and to distinguish it from variability resulting from suboptimal intervention or study designs, it is important that researchers clearly specify the logic of their intervention models, the objectives they wish to achieve (e.g., delay of initiation or prevention of regular alcohol use or binge drinking), and the specific intervention components designed to achieve these objectives.

Specificity in SelfReported Outcome
Measures and Related Issues.The utility and relevance of many preven tion trials also is limited by the lack of outcome measures that specifically assess alcohol use (or use of specific other drugs).Thus, many trials assess substance use in general, without dif ferentiating between alcohol, marijua na, and other illegal drugs.However, some interventions may be effective for preventing the use of one type of drug but not of others.Therefore, to adequately judge the effectiveness of interventions in preventing underage alcohol use, it is important that studies report alcoholrelated outcomes sepa rately from outcomes for other drugs.Moreover, more attention needs to be paid to the validity of the adolescents' selfreported alcohol use because, for example, the settings in which self reports are obtained have been shown to affect reporting (Azevedo et al. 2003).

Limited Replication Study.
Another area of needed improvements concerns the independent replication of existing intervention outcome studies.In addition to simply confirming the initial effects observed for a given intervention, it would be useful to study the effects of systematic variations of the original intervention procedures.For example, one replication study of a schoolbased intervention found that the effectiveness varied depending on whether a teacher or another person implemented the intervention (St.Pierre et al. 2005).At the same time, clear guidelines need to be developed for such replication studies that specify, for example, to what extent the content of an intervention can be modified and a study of it still be considered a replication study (Hawkins 2004;St. Pierre et al. 2005).

Limited Study of Active Ingredients or Core Components and Outcome
Mediators.As mentioned earlier, several of the interventions classified as most promising or mixed or emerging are multicomponent interventions that address more than one domain (e.g., family, school, and community).For these interventions, it may be useful to analyze in more detail which of the components are responsible for the observed effects and what capacity and resources they require for effective implementation.For example, using a strategy called outcome mediator modeling, researchers can identify the key mechanisms underlying observed effects by examining which components of the intervention account for sub stantial proportions of the variance in the targeted alcoholrelated outcomes (Komro et al. 2001).Such analyses are particularly helpful in determining whether individual components differ in their effectiveness and/or whether different components enhance each other's effectiveness (i.e., have syner gistic effects).Similar analyses also can help clarify whether all of the components are necessary to achieve the observed positive effects or whether individual components might be just as effective on their own.

Limited Economic Analyses.
Of the intervention studies reviewed here, only a few included any kind of eco nomic analysis, such as an analysis of the economic benefits specific to alcoholrelated outcomes.The economic analyses that have been conducted to date clearly indicate that several preventive interventions can be cost effective (Aos et al. 2004).Such analyses could be particularly important because if evidencebased interventions can be shown to yield alcoholrelated cost savings, the dis semination of such interventions and their implementation in additional communities might be greatly enhanced.

Limited Study of Factors That Moderate Effects.
It is essential to understand the factors that may moderate (i.e., increase or decrease) the magnitude of the effect of an intervention.This may be especially important in the case of universal interventions that target all members of a certain population.For example, is the intervention equally effective for all members of the population, regardless of their level of risk for alcoholrelated problems?Relatively few analyses of this type have been conducted to date, primarily in the area of schoolbased interventions.However, such analyses are necessary so that in those cases in which the effects of an intervention are not uniform for all participants, the intervention design can be modified appropriately (Brown and Liao 1999;DawsonMcClure et al. 2004;Kellam and Rebok 1992).

Small Samples for Community, Policy, and Environmental
Interventions.Overall, only a few studies of communitybased interven tions were identified that could be included in this analysis (e.g., Communities Mobilizing for Change on Alcohol [Wagenaar et al. 1999] or Community Trials Intervention to Reduce HighRisk Drinking [Grube 1997;Holder et al. 2000]).Moreover, the validity and generalizability of the findings of these studies is limited by the fact that most of them were con ducted in a single community or a small number of communities, and sample sizes were small (Grube 1997;Holder et al. 2000).Thus, future studies of such interventions should involve larger numbers of communities as well as different types of communities (e.g., with respect to population size or ethnic composition and socioeco nomic background of the population).Only under these conditions will researchers be able to identify specific factors that promote or inhibit the success for adapting such interventions to communities other than the ones that were part of the original study sample.

Strong Consistent Standards for Evidence and Research Reporting
The key issues in intervention research listed above that should be addressed in future research of the effectiveness of intervention studies primarily pertain to changes in the design of the studies that can help improve assessment of the validity and generalizability of the results.As described below, another area of intervention research that can benefit from improvements is the development of more universal standards for evaluat ing interventions, conducting replica tion trials, and reporting the results.

Need for Consistency in and Broader Application of Evaluation Criteria.
The number of published criteria used to evaluate evidencebased interventions has increased greatly in recent years.Unfortunately, these criteria vary considerably across pub lications.For example, one study (Lohr 2004) noted that various reviews of evidencebased medicine interven tions used 20 different scales and 11 different checklists to evaluate the degree of efficacy.Because the criteria for the inclusion of effective programs vary, the standards and findings of different evaluations overlap only moderately at best (Mihalic 2004).One way to address such inconsistencies is standardized scoring of the quality of the evidence.Such an undertaking is highly challenging, however, because some qualityofevidence criteria should be weighted more heavily than others (e.g., study design versus other factors of lesser relevance to study validity, such as participant expectations).Study designs differ substantially (e.g., simple designs evaluating a population before and after an intervention versus designs involving random assignment and multiple control groups).Moreover, the same quality criteria would have to be applied to all types of interven tions across all phases of intervention research and across outcomes at all levels, which would not allow for ade quate consideration of studyspecific characteristics and objectives.Finally, it may be difficult to score specific evaluation criteria readily and reliably in studies with complex designs.
The evaluation of prevention pro grams in the area of substance abuse and mental health has improved greatly, but some need for improve ments remains.It would be helpful if researchers consistently used widely accepted and rigorous criteria to assess the efficacy, effectiveness, and dissem ination of preventive interventions, such as those developed by the Society for Prevention Research (Flay et al. 2005;Society for Prevention Research 2004).Although no single method can be used to assess all interventions, these standards note the importance of such general study design components as randomized trials (where feasible); using multiple, unbiased reporters; examining extensive followup effects; or fully reporting all outcome data.According to these standards, an intervention could be considered efficacious (i.e., had a positive effect under the controlled conditions of a clinical study) if it produced consis tent and statistically significant find ings in highquality studies4 and the findings have some practical public health significance.To be considered effective (i.e., have an effect under "reallife" conditions), an intervention also would have to meet additional criteria.For example, the intervention would have to provide means (e.g., manuals or training programs) that allow it to be implemented by third parties and be evaluated under real world conditions using a design that measures the levels of implementation and engagement of the target audience, demonstrates the practical importance of the outcome effects, and specifies the populations to which the findings can be generalized (Flay et al. 2005).
Although meeting the complete set of standards is a goal toward which researchers should aspire, it is recog nized that few intervention research programs meet these standards (for example, availability of replication studies to demonstrate the efficacy of an intervention); accordingly, none of the interventions evaluated in the present analysis fully met these criteria for effectiveness.One of the greatest needs in prevention research is to con duct independent replication studies of existing programs to fully evaluate their efficacy and effectiveness.

Need for Improved Standards Concerning Intervention Replications.
If additional replication studies of existing or new interventions are to be conducted, it also is critical to develop standards for judging when a study is truly a replication or when a program has been changed substantially without appropriate modification of the evaluation such that the subsequent study no longer qualifies as a replica tion study.For example, developers of intervention programs frequently refine their programs based on the results of initial outcome studies, and this refined version may then be disseminated to prospective customers and/or tested in additional studies.Under these circumstances, it would be beneficial to have standards specifying to what extent the study findings on the origi nal version of the intervention still apply to the refined version and whether studies of the refined version can be considered replication studies for the original version of the intervention.

Need for Improved Reporting
Standards.Great variation also exists in the way that data obtained in clinical trials are reported, and often these reports fail to include vital information.To help correct these reporting prob lems, an international group of scien tists developed the Consolidated Standards of Reporting Trials (CONSORT) statement (available at: www.consortstatement.org/consortstatement/overview), which provides a 22item checklist for the transparent reporting of randomized, clinical trials.It covers specific aspects of the various sections that typically are found in scientific reports of clin ical studies (i.e., the background, methods, results, and discussion sec tions) and also provides a standard ized diagram to show the progress of all trial participants from the time they enter the trial and randomly are assigned to a group until the time they leave the trial. 5These reporting standards have now been adopted by more than 150 medical and psycho logical journals, facilitating the evalu ation and interpretation of study results published in those journals.A similar model called Transparent Reporting of Evaluations with Nonrandomized Designs (available at: www.trendstatement.org/asp/statement.asp) has been developed for reporting results of nonrandomized trials.Together with the Society for Prevention Research standards of evidence, these two models can sub stantially improve the validity and 5 This kind of information is useful for judging the efficacy of an intervention because when a study demonstrates that an inter vention is effective with most participants who complete it but that, for example, 80 percent of participants drop out of the trial before it is completed, that intervention needs to be judged differ ently than an intervention that may be effective in a smaller pro portion of participants but in which almost all participants have completed the study.
interpretability of the results of preventive intervention studies.

Adopting Public Health Impact-Oriented Models
To have an impact on public health, there are several steps that should be taken.To begin, there is a need for development and testing of a broader range of interventions-across devel opmental phases, domains, and populations-so that the needs of all populations, particularly those that are underserved, are appropriately addressed.Importantly, in addition to testing and demonstrating favorable results on outcome measures, interven tions also must be suitable for larger scale implementation.Studies already have identified some key factors that promote effective dissemination of evidencebased inter ventions and thereby help achieve a broad public health impact.These factors include, for example (Dearing 2004;Elliot and Mihalic 2004): • The readiness and capacity of orga nizations to implement interventions; • The quality of training and techni cal assistance available to the people administering the intervention; and • Support from administrators in the implementation system.
Similarly, information is available on factors that influence the quality of implementation and its sustainability as well as on barriers to dissemination of public health interventions.
One approach to achieving public health impact is to adapt existing models of prevention intervention research.For example, the Institute of Medicine (Mrazek and Haggerty 1994) proposes that the design and initial testing of an intervention should be guided by theories on development and underlying factors related to a disorder.Based on the results of the initial tests, the intervention then should be refined before it is subjected to rigorous studies assessing its efficacy under controlled conditions.Subsequent replication studies and effectiveness studies under realworld conditions should determine the extent to which the intervention produces positive results with different populations and in different settings.Only after this comprehensive process has been com pleted would the intervention be ready for widespread dissemination.Although this model already provides many benefits, newly emerging models building on it seek to further enhance the dissemination and public health impact of preventive interventions.These models emphasize, for example, enhanced participation of communi ties as well as more consumeroriented approaches during all stages of the research (Greenberg et al. 2003;RotheramBorus and Duan 2003;Sandler et al. 2005;Spoth et al. 2005).These emerging models incor porate private enterprise procedures for product development and market ing that take into consideration relevant consumer, provider, and funder issues and may thereby help optimize effective, broad based dissemination.Other approaches incorporate community-university partnership models because some data have indicated that community teams supported by communi ty-university partnerships can effec tively engage potential participants in evidencebased interventions that can be implemented with high quality on a sustained basis, resulting in a range of positive, communitylevel out comes (Spoth et al. 2007a,b).
Finally, as with other behaviorally oriented approaches to controlling a chronic disease, the translational aspect of interventionrelated research needs to be emphasized.For example, basic causes of underage drinking (e.g., the role of peer and family influences on adolescents' drinking behavior) are translated into realworld applications.To achieve this, researchers from various disciplines need to work together to stimulate the translation of science into practices that can have a public health impact and/or accelerate the rate at which effects of the interven tions are seen at the population level (Spoth 2009); the Society for Prevention Research has developed a framework for advancing this type of translational research (see http://www.prevention research.org/).
Although some gaps still remain in the development, evaluation, and dissemination of interventions to prevent underage drinking, the existing and emerging models offer great promise for ultimately reducing the substantial public health burden of underage drinking and its associated impacts.To realize the full benefits of these approaches, however, it also is critically important that the necessary resources are available as well as suffi cient funding.

Conclusions
Over the past few decades, much progress has been made in the devel opment of interventions to prevent underage drinking, and several inter ventions that can reduce the rate of alcohol use in underage populations and/or promote protective factors are now available.This progress has result ed, at least in part, from substantial methodological improvements in study design and analysis, such as the increased evaluation of interventions using stringent randomized clinical trials.Despite this progress, however, the full potential of such preventive interventions has not yet been reached.For example, as described in the pre ceding sections, not all developmental stages, population subgroups, and intervention domains are adequately covered by existing interventions.Evidence and reporting standards also warrant further improvements, as do intervention research models and strategies to enhance dissemination and quality of implementation, and sustainability of evidencebased inter ventions in realworld settings.Finally, to achieve greater public health impact it will be essential to mobilize sufficient resources to provide the infrastructure and capacity necessary to support research on and highquality, sustained implementation of interventions at all levels.■

Table 1
Interventions Aimed at Different AgeGroups of Adolescents With Some Level of Evidence of Effect NOTE: For a description of the various interventions and their evidence, see Table2 and Spoth et al. 2008.

Table 2A
Summary of Preventive Interventions Classified As Most Promising Targeting Adolescents in Three Different AgeGroups

Table 2B
Summary of Preventive Interventions Classified As Most Promising Targeting Adolescents in Three Different AgeGroups

Table 2C
Summary of Preventive Interventions Classified as Most Promising Targeting Adolescents in Three Different AgeGroups